This invention relates to ring-type networks for digital communication.
In ring networks, a number of nodes are interconnected by communication links to form a continuous ring. The devices (called DTEs) which use the network (for example, terminals or microcomputers) are connected to the nodes (called DCEs). Digital data is sent around the ring from node to node in a particular direction. Information to be sent from a given DTE passes via its node onto the ring, around the ring to the node of the recipient DTE, and then on to the recipient DTE.
To enable different DTEs to share the ring, protocols have been established to define the form in which digital data is sent around the ring.
For example, in token ring protocols, digital data is sent in packets. Each packet includes bits showing the source and destination of the packet together with a number of bits of data. All of the bits of a packet are carried on the ring one after the other without any intervening dead time. At a later time another related packet is sent.
In a so-called slotted ring scheme, when a node is ready to send data it seizes the first available empty packet, inserts the data into the packet, and redelivers the packet to the ring.
Tukeyama, "Major and Minor Ring Architecture Using Fiber Optics," discloses a ring network in which the communication links are optical fibers. Data is carried around the ring in frames each of which includes a fixed number of multi-bit slots. The slots which occupy the same relative position in successive frames, for example the third slot each frame, make up a 2.4 megabit per second channel.